Este sensor abaixo pode ser comprado nos sites da china por menos de R$40,00.

yum install gcc libusb-devel libusb

# download software:
wget https://blog.abratel.com.br/wp-content/uploads/2014/11/pcsensor-master.tar
# unzip
tar -zvf pcsensor-master.tar
cd pcsensor-master
make clean
make
cd /usr/src/pcsensor
./pcsensor
     2014/11/13 12:57:38 Temperature 81.72F 27.62C



[root@zeus uferes]# whereis lsusb
lsusb: /sbin/lsusb /usr/share/man/man8/lsusb.8.gz
[root@zeus uferes]#  /sbin/lsusb
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 005 Device 002: ID 0557:2304 ATEN International Co., Ltd
Bus 006 Device 001: ID 0000:0000
Bus 008 Device 001: ID 0000:0000
Bus 003 Device 005: ID 0c45:7401 Microdia TEMPer Temperature Sensor

Criar script para nagios check_temper

#!/bin/bash
# script para checar a temperatura do DC
# exit 1 = warning; exit 2 = Critico; exit 3 = Unknown


tempe=$(/usr/local/bin/pcsensor | awk '{print $5} ' | cut -c 1-2)
temperatura=$(/usr/local/bin/pcsensor)
if [ $tempe -lt "32" ] ;  then # se for menor (is less)
        echo "Temperatura atual do Data Center: $temperatura"
        exit 0;
elif  [ $tempe -lt "34" ] ;  then
        echo "Temperatura no Data Center: $temperatura"
        exit 1;
elif  [ $tempe -lt "60" ] ;  then
        echo "Temperatura no Data Center: $temperatura"
        exit 2;
else
        echo "Aguarde nova checagem de temperatura em 2 minutos..."
        exit 3;
fi
exit 3;

Para testar o termometro ligado em outro servidor:

services.cfg

define service{
  use                             local-service         ; Name of service template to use
  host_name                       servidor_em_que_esta_o_termometro
  service_description             Checa a temperatura no DataCenter
  check_command                   check_themper_by_ssh
  check_period                    24x7
  }

define command {
        command_name check_themper_by_ssh
        command_line  $USER1$/check_by_ssh -H $HOSTADDRESS$ -4 -C "sudo /usr/src/pcsensor/check_themper"
}

Para usar no nagios do proprio servidor:

define service{
  use                             local-service         ; Name of service template to use
  host_name                       localhost
  service_description             Checa a temperatura no DataCenter
  check_command                   check_themper
  check_period                    24x7
  }

define command {
        command_name check_themper_by_ssh
        command_line  $USER1$/check_themper
}